1. Field of the Invention
The present invention relates to an integrated circuit test system and method, in order to enable the continuous exchange of numerous integrated circuits and a test work, while preventing the occurrence of frost in a very low temperature environment.
2. Description of the Related Art
As circuit density continues to increase, the testing of Soc (System On a Chip) products becomes ever more important. Such testing is provided to determine whether electrical characteristics of the products operate normally, while the operating environment varies. For example, the circuit under test can be subject to an HVS (High Voltage Stress) test based on a gradually varied use range of the products and subject to an extreme environment test, e.g., of high temperature, low temperature and very low temperature. Especially, in the test involving the ranging temperature environment, varying between a high temperature and a very low temperature, the test ensures the practical use of the product.
Testing under a low temperature and a very low temperature atmosphere is more difficult than testing under a high temperature atmosphere. In forming the low and very low temperature atmosphere, moisture that is present in the ambient air is condensed into a solid state and then is formed as frost, on an excessively cooled sample and on portions of respective components electrically connected to the sample. This causes a leakage current, and a repeated shrinkage and expansion of the condensed moisture causes potential damage and breakage of the sample and the respective components.
A conventional integrated circuit test system and method under a low or very low temperature environment is now described as follows, with reference to the accompanying drawings.
With reference to FIGS. 1 and 2, the conventional integrated circuit test system includes a tester 10 having a plurality of channel cards 12 for executing an electric characteristic test of an integrated circuit (IC); a test board 20, which is referred to as a wiring board or a performance board, and which is electrically connected to the tester 10 containing the channel cards 12 and is equipped with various circuit components 22 necessary for a test of the IC; and a temperature controller 30 positioned on one side of the tester 10, for generating air as a desired temperature level and providing the IC mounted on the test board 20 with the temperature-controlled air.
The tester 10 includes a test head part 14 equipped on a portion thereof, which executes a test using the plurality of channel cards 12.
The test head part 14 includes a mounting member 14a on an upper face circumference thereof the mounting member 14a electrically connecting the test board 20 with channel terminals 12a of the channel cards 12.
The tester 10 is provided with a manipulator 16 on another portion thereof, the manipulator 16 controlling the progression of a test by a worker; an output part 18 such as a monitor etc. for checking status of the progression; and a computation part or a computer etc. (omitted for a brevity of the drawings), for managing and executing computations related to testing.
The test board 20 mounted through the mounting member 14a of the tester 10 includes a socket 24 for receiving an IC via an electrical connection; various circuit components 22 necessary for the test of the IC; and a circuit pattern (omitted for the brevity of the drawings) having an electrical connection with the channel terminals 12a of the channel cards 12.
The various circuit components 22 can be provided as active elements such as a resistor, a condenser and an inductor, and as switching devices such as a relay, so as to prevent a drop of characteristic caused by noise generated in a test procedure of the IC. These circuit components 22 are installed, preferably, approximately near the socket 24, via soldering.
The temperature controller 30 equipped on one side of the tester 10 includes an air forming part 32 for eliminating moisture present in the ambient air and simultaneously generating air at the desired low temperature level. The air at a low temperature and moisture formed in the air forming part 32 flows through a supply line 34 that is extended to a position face to face with the IC mounted to the test board 20.
The supply line 34 is provided with a supply nozzle 36 on an end part thereof, which is positioned to rise and set against the IC mounted to the test board 20, and for selectively supplying air at the low temperature and moisture.
The supply nozzle 36 is equipped with a guide pipe 38 that is, partially or entirely, made of transparent material and that surrounds around an end outer portion of the supply nozzle 36 in a pipe shape.
The guide pipe 38 controls air supplied through the supply nozzle 36 to be distributed restrictedly within the IC and nearby to its perimeter.
In addition, a withdrawal line 40 is connected to an upper part side of the guide pipe 38, to withdraw and return the supplied air of low temperature/moisture to the air forming part 32.
Operations of the respective components will now be described as follows.
A sampling IC is mounted on the test board 20, and then the temperature controller 30 positions the supply nozzle 36 over the IC. At this time, the guide pipe 38 is positioned close to the test board 20 as shown.
Then, the temperature controller 30 maintains a low moisture state on the IC and its peripheral region, and continuously supplies air at a low temperature, to thereby cool the IC to the desired temperature level. The supplied air of low temperature and moisture is distributed limitedly to the area range of the guide pipe 38. This air is partially re-circulated through the withdrawal line 40, and the remaining air is externally discharged through a gap between the guide pipe 38 and the test board 20.
When the IC is cooled to the desired level through such a procedure, a worker executes a test procedure using the test board 20 electrically connected to the IC and using the channel cards 12 in the tester 10.
As described above, in the midst of the test procedure, air present under the test board 20 is condensed into a solid state, namely, formed as frost, due to the excessive cooling atmosphere, on the test board 20 and on the various circuit components 22. Such frost has a continuous crystal growth, and thus causes a failure such as a leakage current on the respective components having an electrical connection. Furthermore, the leakage current commonly occurs simultaneous with the start of the test under a very low temperature atmosphere of about −90° C., etc., which is a serious limitation.
According to a conventional technology to address this problem, a sealing member 26 having a shield plate 26a is mounted to a rear portion of the cooled test board 20 for cutting off the invasion of moisture. Also, on the test board 20, a through-hole 28 is formed so as to supply air of low temperature/moisture to a lower side of the test board 20 provided by the installation of the sealing member 26.
But, separately from such above-mentioned conventional technology to solve the problems, during the exchange of an IC that has completed the test, the excessively cooled sample is exposed to air, and frost is generated on the sample and respective components of the tester 10, containing the socket 24 and the test board 20 electrically connected to the sample, which can lead to a failure. In particular, the sample and components can be damaged and cracked by the physical force of shrinkage and expansion due to frost.
To solve these problems, the sample and the respective excessively cooled components must be again slowly returned to a normal temperature state, and the sample must again slowly be cooled so as to maintain low moisture after the exchange of the samples. These required procedures cause an inconvenience, require an excessively long time to progress. Furthermore, this shortens the useful life of the test board 20 and the respective components influenced by frost, to thus, again, affect the economy of manufacturing.